Terrace Waterproofing

In India, Terrace Waterproofing has always been done with very traditional materials. Typically systems like brickbat Coba, Lime terracing or the “Mud Fuska” technique are still very much in vogue. These systems have been offering waterproofing with some insulation against heat.

Some of the problems that these systems have are:

  • Heavy loading on the slab
  • Cracks on the surface, especially in case of brick bat coba
  • Expertise levels of application required for lime terracing/mud fuska not as good as in the olden days
  • Offer more insulation rather than a leak proof or a water-tight system
  • As they age breaking them and re-doing the same system is risky for the slab; cracks caused in the slab increase the problem of leakage

Simple steps can be taken up for new terrace waterproofing in case of both new & existing terrace slabs.

Some points for waterproofing contractors have been listed as under, to increase their rate of success, in carrying out the waterproofing jobs on terraces/roofs.

Structural Issues

Cause of Leakage:

  1. Cracks on the top surface of slab-Injection grouting as required, large cracks repair with URP modified mortar
  2. Cracks on the bottom of slab due to excess deflection of slab-Structural consultant’s opinion must be taken; if leaking can be addressed with a hydrophobic PU foam injection grout
  3. Cracks at column supports-Structural consultant’s opinion must be taken
  4. Excess porosity in the slab, bad quality concrete-Resort to Injection grouting
  5. Expansion joint in the slab-Polysulphide sealant application with proper detailing
  6. Inadequate design of the slab-Structural engineers opinion
  7. Spalling of concrete due to corrosion in the slab-Detailed repair with catholic protection & repair materials
  8. Cracks due to differential settlement of a building-structural and soil experts opinion must be taken

As the case may be, these must be addressed before waterproofing job is taken up.

Non Structural Issues:

  1. Slope not proper-Slope must be provided for water drainage
  2. Inadequate rain water pipes-Provide drain water pipes as required
  3. Parapet wall not in good condition-Repair parapet masonry/plaster using mortar added with w/p compounds/polymer bonding agents
  4. Internal cracks, honeycombs (finished with ordinary mortar), porosity, etc. which cannot be seen by eye-pack using inject grout at the place of leakage from top to bottom
  5. Mechanical installations like cooling towers, AC units, etc., on the terrace-Foundations must be examined and repaired if required
  6. Aggressive climatic conditions-choose and apply protective coating/WP system
  7. Thermal extremes-Provide insulation treatment over WP layer.

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